PCI-SIG's new PCIe 4.0 bus will be finalized by 2014 or 2015

A speedy successor to PCI data transfer protocols used in PCs and interconnects like Intel's Thunderbolt is being designed with tablets in mind, a standards-setting organization said on Tuesday.

The PCI-Express 4.0 bus will also go into PCs, servers, and embedded devices and will provide more bandwidth for high-speed data transfers than its predecessors, which could boost overall tablet and PC performance, said Al Yanes, president and chairman of the PCI Special Interest Group, which develops the PCI standard. The organization on Tuesday wrapped up a feasibility study that sets the stage for the final specification to be released by 2014 or 2015.

The PCI-Express protocol is used in PCs to shuttle data at high speeds between internal components. A version of the PCI-Express is also supported on Thunderbolt, an interconnect technology co-developed by Intel and Apple.

The protocol, also called PCIe 4.0, will transfer data at up to 16 gigatransfers per second over copper wire. That is twice the speed of PCIe 3.0, which was finalized in late 2010 and is just reaching products. Intel is bringing on-chip support for PCIe 3.0 with its upcoming Ivy Bridge desktop and laptop processors, which will be released in the first half next year.

There are implementations of the older PCI buses in tablets, but they do not run demanding workloads, said Dean McCarron, principal analyst at Mercury Research. But the tablet market is evolving fast, and there will be a bigger need for a faster bus like PCI-Express 4.0 to play high-definition games and video, he said.

"Performance requirements always increase. This is not for a product for tomorrow, but for a product down the road," McCarron said. "Look at phones, they started with LCDs or LEDs, but now they are pushing high-definition."

PCI-SIG is trying to cut down on power consumption by chopping the number of data-transfer lanes and reducing on-board hardware, McCarron said. That also helps reduce the cost of making a tablet.

Beyond an internal bus, PCI-SIG is also mulling plans to create a thin interconnect to link mobile devices such as smartphones and tablets to external peripherals, though plans have not yet been fully detailed. The peripheral would rival existing interconnects like USB, Thunderbolt, and FireWire.

PCIe 4.0 is more about performance than power savings, and addresses the need to bring faster communication interfaces to take advantage of technologies such as 100-gigabit Ethernet and solid-state drives, said Nathan Brookwood, principal analyst of Insight 64.

The first products with PCIe 4.0 will be on computers where performance is never enough, such as servers and gaming desktops and laptops, Brookwood said. Putting PCIe 4.0 into tablets could be a long-term plan, and could relate to a time when tablets start blending in with low-end notebooks.

The final PCIe 4.0 specifications are expected to be released in the 2014 to 2015 time-frame, Yanes said. He said that PCI technologies are typically implemented in products within a year after a specification release, but that actual product release dates depended on device makers. The PCI-SIG currently has more than 800 members.